/* 公共方法封装 */

var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; var base64DecodeChars = new Array(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);
const base = {

  Base64(str) {
    var out, i, len;
    var c1, c2, c3; len = str.length; i = 0; out = ""; while (i < len) {
      c1 = str.charCodeAt(i++) & 0xff; if (i == len) { out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt((c1 & 0x3) << 4); out += "=="; break; } c2 = str.charCodeAt(i++); if (i == len) {
        out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4)); out += base64EncodeChars.charAt((c2 & 0xF) << 2); out += "="; break;
      } c3 = str.charCodeAt(i++); out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4)); out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6)); out += base64EncodeChars.charAt(c3 & 0x3F);
    } 
    return out;
  },
  //将Ansi编码的字符串进行Base64编码
  encode64(input) {
    var output = "";
    var chr1, chr2, chr3 = "";
    var enc1, enc2, enc3, enc4 = "";
    var i = 0;
    do {
      chr1 = input.charCodeAt(i++);
      chr2 = input.charCodeAt(i++);
      chr3 = input.charCodeAt(i++);
      enc1 = chr1 >> 2;
      enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
      enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
      enc4 = chr3 & 63;
      if (isNaN(chr2)) {
        enc3 = enc4 = 64;
      } else if (isNaN(chr3)) {
        enc4 = 64;
      }
      output = output + keyStr.charAt(enc1) + keyStr.charAt(enc2)
        + keyStr.charAt(enc3) + keyStr.charAt(enc4);
      chr1 = chr2 = chr3 = "";
      enc1 = enc2 = enc3 = enc4 = "";
    } while (i < input.length);
    return output;
    },
  //将Base64编码字符串转换成Ansi编码的字符串
  decode64(input) {
    var output = "";
    var chr1, chr2, chr3 = "";
    var enc1, enc2, enc3, enc4 = "";
    var i = 0;


    if (input.length % 4 != 0) {
      return "";
    }
    var base64test = /[^A-Za-z0-9\+\/\=]/g;
    if (base64test.exec(input)) {
      return "";
    }
    do {
      enc1 = keyStr.indexOf(input.charAt(i++));
      enc2 = keyStr.indexOf(input.charAt(i++));
      enc3 = keyStr.indexOf(input.charAt(i++));
      enc4 = keyStr.indexOf(input.charAt(i++));
      chr1 = (enc1 << 2) | (enc2 >> 4);
      chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
      chr3 = ((enc3 & 3) << 6) | enc4;


      output = output + String.fromCharCode(chr1);
      if (enc3 != 64) {
        output += String.fromCharCode(chr2);
      }
      if (enc4 != 64) {
        output += String.fromCharCode(chr3);
      }
      chr1 = chr2 = chr3 = "";
      enc1 = enc2 = enc3 = enc4 = "";
    } while (i < input.length);
    return output;
    },
  utf16to8(str) {
    var out, i, len, c;
    out = "";
    len = str.length;
    for (i = 0; i < len; i++) {
      c = str.charCodeAt(i);
      if ((c >= 0x0001) && (c <= 0x007F)) {
        out += str.charAt(i);
      } else if (c > 0x07FF) {
        out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
        out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
        out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
      } else {
        out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
        out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
      }
    }
    return out;
    },
  utf8to16(str) {
        var out, i, len, c;
        var char2, char3;
        out = "";
        len = str.length;
        i = 0;
        while (i < len) {
          c = str.charCodeAt(i++);
          switch (c >> 4) {
            case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
              // 0xxxxxxx
              out += str.charAt(i - 1);
              break;
            case 12: case 13:
              // 110x xxxx   10xx xxxx
              char2 = str.charCodeAt(i++);
              out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
              break;
            case 14:
              // 1110 xxxx  10xx xxxx  10xx xxxx
              char2 = str.charCodeAt(i++);
              char3 = str.charCodeAt(i++);
              out += String.fromCharCode(((c & 0x0F) << 12) |
                ((char2 & 0x3F) << 6) |
                ((char3 & 0x3F) << 0));
              break;
          }
        }
        return out;
        }

  
};

module.exports = base; 